1. Field of the Invention
This invention relates to a test fixture capable of simultaneously testing a plurality of contacts arranged in a planar array on an integrated circuit die. More particularly, the invention relates to a test fixture having a contact member containing a plurality of electrical contacts which may be simultaneously urged under pressure against a plurality of contacts on an integrated circuit chip or die.
2. Description of the Related Art
Testing of conventional integrated circuit dies having contacts arranged around the periphery of the die may involve the use of catwhisker probes or test sockets with wiper contacts.
However, the testing of contacts on an integrated circuit die which may be arranged in a two dimensional array of contacts for subsequent connection to a two dimensional array of parallel leads as described in Brown U.S. Pat. No. 4,616,406, assigned to the assignee of this invention, creates problems in attempting to use such conventional testing apparatus because of the two dimensional array disposition of the contacts, and more particularly because of the relative inaccessibility of the inner contacts in the contact array.
One approach suggested was to provide a test fixture comprising an interconnect substrate with an array of pads arranged in general registry with an array of contacts or pins on an integrated circuit die. A special elastomer with conductive particle loading which would provide conductivity only in the direction of compression would be interposed between the integrated circuit die and the test fixture and then pressure would be applied to urge the die and the test fixture together.
However, it was found that the presence of the polymer between the contacts on the die and the contacts on the test fixture, while providing sufficient electrical contact, failed to provide adequate heat transfer from the contacts on the die to the contacts on the test fixture during the testing since the polymer, while providing electrical conductivity, did not provide sufficient thermal conductivity.
What is needed is a test fixture capable of simultaneously electrically connecting to all of the contacts on a die or chip, regardless of the location of the contacts on the die, which will provide high performance including high throughput rates and good thermal dissipation of the heat generated during the testing operation. Preferably, the test fixture should also be capable of dealing with the problem of oxide formation on the chip contacts which can result in faulty test results due to open circuits or high contact resistance.